Method of quench hardening with oil comprising mono (polyisobutenyl) succinimide

ABSTRACT

A quenching oil composition for simultaneously hardening ferrous metals and imparting excellent cleanliness or brightness to the metal surface comprises a major portion of a mineral oil with high heat-exchange rate containing a minor proportion of an ashless mono(polyisobutenyl) succinimide.

United States Patent 1191 Wilpers Feb. 18, 1975 METHOD OF QUENCH IIARDENING WITH OIL COMPRISING MONO (POLYISOBUTENYL) SUCCINIMIDE [75] Inventor: Dale J. Wilpers, Godfrey, Ill.

{73] Assignee: Shell Oil Company, Houston, Tex.

[221 Filed: Dec. 21, 1973 [21] Appl. No.: 427,204

52 us. Cl ..l48/20.6, 148/29, 148/143,

[51] Int. Cl C2ld l/44 [58] Field of Search 148/29, 206, 143, 28; 252/75, 77, 78

[56] References Cited UNITED STATES PATENTS 3.224910 12/1965 EcEwen 148/143 Riggs 148/28 Carver et a1. 148/206 Primary Examiner-Walter R. Satterfield Attorney, Agent, or Firm-Henry C. Geller [57] ABSTRACT 4 Claims, No Drawings METHOD OF QUENCI-I HARDENING WITH OIL COMPRISING MONO (POLYISOBUTENYL) SUCCINIMIDE BACKGROUND OF THE INVENTION The method of hardening ferrous materials by heating them to a temperature above 1,600F and then rapidly cooling them in order to increase the hardness is well known. The cooling step in this procedure is termed quenching." It is also known that an increase in the speed of quenching results in increased metallic hardness. Hydrocarbon oils, in particular mineral oils, are commonly used as quenching liquids. A few mineral oils naturally have a high heat-exchange rate and can be used as is for quenching oils. But in general straight mineral oils do not usually form satisfactory quench media since the initial rate of cooling is too slow. It has been assumed that the widely different quenching speeds between a few and most oils is due to presence or absence of compositional components in very small concentration. Hence, the development of the quenching oil art has been in the direction of modifying hydrocarbon oils by incorporating certain additives therein. The state of the art is such that many various different additives have been used for this purpose; see, for example, U.S. Pat. No. 3,729,417, issued Apr. 24, 1973. Illustrative of these additives for im; p roT/ing cooling rate are ash-forming materials such as oil-soluble alkali metal and/or alkaline earth metal petroleum sulfonates, e.g., calcium, sodium, or barium sulfonates. Such materials leave behind on the metal an ash or deposit which affects the brightness or cleanliness of the metal surface. These deposits are difficult to wipe off or remove from the metal surface. The two most important aspects of quenching oil performance are hardening ability and cleanliness of quenched metal surface. The problem is that high-speed quenching oils, which have good hardening ability, usually produce unclean or stained metal surfaces. In one solution to the problem, copending aplication U.S. Ser. No. 373,065 filed June 25, 1973, discloses an oil composition which contains an effectve additive that facilitates rapid heat exchange between the metal and the oil composition in the heat treating process, such as the hardening of steel, and which leaves on heat-treated metal surfaces an easily removable flaky deposit. However, it would be an advance in the art to provide a high-speed quenching oil composition capable of producing bright quenched ferrous metal surfaces.

SUMMARY OF THE INVENTION It has now been found that a non-staining, i.e., bright high-speed quenching oil consists essentially of a mineral oil having a high heat exchange rate as measured by a GMC Magnetic Quenchometer Time of from about 9 to about seconds whch contains dissolved therein a minor amount within the range of from about 0.1 percent to about 10% by weight of a critically specific detergent-type composition. The specific detergenttype component required for the non-staining quenching oil composition of the invention is a mono (polyisobutenyl)-substituted succinimide of tetraethylenepentamine. An improved method for quenching metals, especially steel, is obtained by use of the abovedefined quenching oil.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mineral oil base, which in addition to the additive is a critical feature of the invention, must have not only thermal and oxidative resistant properties capable of meeting the requirements desiied in a quenching oil, but also must process a high heat-exchange rate. The high heat-exchange rate required. by the mineral oil component of the composition of the invention can be indicated by or defined in terms of quenching time as measured in the GMC Magnetic Quenchometer Test. This test takes advantage of the fact that metals lose their magnetic properties when heated above a critical temperature called the Curie Point and regain it when cooled. Polished nickel balls, preheated to 1,625F in a muffle furnace, are dropped past a photoelectric cell into a measured volume of oil located in a magnetic field. When the nickel ball cools to its Curie point, approximately 670F for pure nickel, it regains its magnetic properties and is drawn to a magnet. An electric timer, which is engaged when the nickel ball passes the photoelectric cell, is automatically stopped when the ball is drawn to the magnet. The recorded time in seconds is reported as the quenching time of the sample or oil being tested. The lower the quenching time reported, i.e., the smaller the number of Seconds, the faster is the speed of the quenching oil and the greater its cooling effectiveness. For the purposes of the composition of the invention the mineral oil component must possess a quenching time in the range of from about 9 to about 15 seconds as measured in the above-described GMC Magnetic Quenchometer Test. Oils which possess a quenching time in this range are high-speed quenching oils. As mentioned previously a few mineral oils naturally have a high heat-exchange rate and can be used as is for the high-speed quenching mineral oil component of the composition of the invention. Also useful as the mineral oil component of the composition of the invention are certain mineral oils containing ashless additives to improve the quench speed thereof such as disclosed in the above-mentioned copending application U.S. Ser. No. 373,065, filed June 25, 1973, wherein is disclosed quenching oil with an improved rate of cooling consisting essentially of a mineral oil having a viscosity of from about 15 to about 200 SUS at F and an aromatic content of 8 to 60 percent which contains dissolved therein a critical amount within the range of from about 0.005percent to about 0.04 percent by weight of a vicinal dihydrocarbyl-substituted 2-mercaptothiazole, each hydrocarbyl being preferably of l to 6 carbon atoms. In summation, the mineral oil component of the composition of the invention may be a high-speed quenching mineral oil alone or a high-speed quenching mineral oil containing additives to improve the quench speed of the mineral base oil such that, in all cases, the mineral oil component of the invention as so examplified above has a quenching time of from about 9 to about 15 seconds as measured in the GMC Magnetic 'Quenchometer Test.

The critically specific detergent-type component required for the non-staining quenching oil composition of the invention may be defined as a mono (polyisobutenyl)-substituted succinimide of tetraethylenepentamine wherein the molecular weight of the polyisobutenyl substitutent is from about 700 to about 3 5,000 and preferably from about 2,000 to about 4,000.

The concentration of the mono (polyisobutenyl) succinimide additive component reqired for the oil compositions of the invention is from about 0.1 percent to about 10.0 percent by weight, based on the amount of the mineral oil component of the invention. A preferred range ofmonopolyisobutenyl) succinimide additive is from 0.5 percent to 5.0 percent by weight and most highly preferred is about 2.5 percent by weight.

The compositions of the present invention, which contain the above-defined monopolyisobutenyl) succinimide additive, can be further improved with respect to oxidation stability by addition thereto of phenolic antioxidants, amine antioxidants and the like.

EXAMPLE I The mineral oil component alone and the mineral oil component together with the indicated concentration of additive given below and the effectiveness thereof as non-staining high-speed quenching oils is demonstrated by testing the compositions in the GMC Magnetic Quenchometer Test. This test has been described hereinabove for the determination of the speed of quenching time. The test is also determinative of the quenched metal surface brightness or non-staining effectiveness of a quenching oil composition in the following manner. The polished nickel balls used in the determination of the quenching time (GMC Quenching Time, seconds) are given a cleanliness rating, after the quenching time is obtained, which is determined by the appearance of the quenched nickel balls. The cleanliness or brightness rating is indicative of the non-staining effectiveness of the quenching oil composition and the rating is expressed as a letter from A" through E" inclusive where the letter rating is defined as follows:

A zero to trace deposits B trace to light deposits C light deposits modified test consists of dropping a standard GMC Magnetic Quenchometer test ball (i.e., a polished nickel ball) preheated to 1,625F in a muffle furnace, into 260 grams of quenching oil to be tested and stirring the oil rapidly for 15 minutes. The ball is then letter rated for surface deposit by the above-defined letters ranging from A through E. Next the ball is wiped with a towel and letter rated again. In Table 1 below,

run 1 gives data and results from the mineral oil component alone without detergent-type additive; runs 2 and 3 indicate the effectiveness of the additive compositions of the invention; and runs 4 through 7 containing additives not according to the invention are included to show how additives of similar detergent type or similar chemical content are far less effective than the compositions of the invention in high-speed, nonstaining quenching of metal. The mineral oil component used as base oil in Table I below has the following composition:

"/0 volume "/1 weight HVl 100 Neutral 78 3g HVl I50 Bright stock 7 99.75

' Low viscosity mineral oil (40-47 SUS at l00F) l5 lonol" antioxidant 0.25 (2,6-diterL-butyl-4- methylphenol) Table 1 GMC Magnetic Modified Test Quenchometer Test Quenched Metal Quenching Quenching Surface Brightness Time Metal Surface Before After Run Test Oil (sec) Brightness Wiping Wiping 1. Base oil alone 1 1.8 D D D 2. Base oil 5%w of 12.0 C B A mono(polyisobutenyl) succinimide of tetraethylenepentamine; mol.wt. polyisobutenyl group within range of from about 700 to about 5,000. 3. Base oil 5%w of 12.6 C B A mono(polyisobutenyl) succinimide of tetraethylenepentamine; mol.wt. polyisobutenyl group within range of from about 2.000 to about 4,000. 4. Base oil 571w of 1].) C C C polyisobutenyl succinimide of compound.

Table I -Continued GMC Magnetic Modified Test Quenchometer Test Quenched Metal Quenching Quenching Surface Brightness Time Metal Surface Before After Run lust Oil (sec) Brightness Wiping Wiping 5. Base oil 571W of 11.4 C C C hisl polyisobutenyl) succinimide of tetraethylenepentamine. 6. Base oil 57zw ofa l 1.2 D D D polyisobutenyl succinic acid dicster of a polyol 7. Base oil 5'7zw of 13.3 D D D Mannich base (aldehyde-amine) detergent containing about 0.3%w boron.

I claim as my invention: to about 5,000.

1. ln a method of quenching, useful in hardening of ferrous metal, wherein a metal to be treated is heated to an elevated temperature and wherein said heated metal is then rapidly quenched in a quenching medium to increase the hardness in said metal, the improvement for simultaneously hardening said metal and imparting brightness to the metal surface which comprises using as said quenching medium a composition consisting essentially of a major portion of a mineral oil, having a high-heat exchange rate as measured by magnetic quenchometer time of from about 9 to about 15 seconds, and from about 0.1 to about 10 percent by weight of a mono(polyisobutentyl)-substituted succinimide of tetraethylene-pentamine wherein the polyisobutenyl substitutent has a molecular weight of from about 750 LII 2. The method of claim 1 wherein the mineral oil with high-heat exchange rate is a mineral oil, having a viscosity of from about 15 to about 200 SUS at l0OF and an aromatic content of from 8 to 60 percent, which contains from about 0.005 to about 0.04 percent by weight of a vicinal dihydrocarbyl-substituted 2- mercaptothiazolc, each hydrocarbyl substituent having from 1 to 6 carbon atoms.

3. The method of claim 1 wherein said succinimide is present in an amount of from about 0.5 to about 5 percent by weight.

4. The method ofclaim 1 wherein said polyisobutenyl group has a molecular weight of from about 2.000 to about 4,000. 

000.
 1. IN A METHOD OF QUENCHING, USEFUL IN HARDENING OF FERROUS METAL, WHEREIN A METAL TO BE TREATED IS HEATED TO AN ELEVATED TEMPERATURE AND WHEREIN SAID HEATED METAL IS THEN RAPIDLY QUENCHED IN A QUENCHING MEDIUM TO INCREASE THE HARDNESS IN SAID METAL, THE IMPROVEMENT FOR SIMULTANEOUSLY HARDENING SAID METAL AND IMPARTING BRIGHTNESS TO THE METAL SURFACE WHICH COMPRISES USING AS SAID QUENCHING MEDIUM A COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PORTION OF A MINERAL OIL, HAVING A HIGH-HEAT EXCHANGE RATE AS MEASURED BY MAGNETIC QUENCHOMETER TIME OF FROM ABOUT 9 TO ABOUT 15 SECONDS, AND FROM ABOUT 0.1 TO ABOUT 10 PERCENT BY WEIGHT OF A MONO(POLYISOBUTYENTYL)-SUBSTITUTED SUCCINIMIDE OF TETRAETHYLENEPENTAMINE WHEREIN THE POLYISOBUTENYL SUBSTITUTED HAS A MOLECULAR WEIGHT OF FROM ABOUT 750 TO ABOUT 5,000.
 2. The method of claim 1 wherein the mineral oil with high-heat exchange rate is a mineral oil, having a viscosity of from about 15 to about 200 SUS at 100*F and an aromatic content of from 8 to 60 percent, which contains from about 0.005 to about 0.04 percent by weight of a vicinal dihydrocarbyl-substituted 2-mercaptothiazole, each hydrocarbyl substituent having from 1 to 6 carbon atoms.
 3. The method of claim 1 wherein said succinimide is present in an amount of from about 0.5 to about 5 percent by weight.
 4. The method of claim 1 wherein said polyisobutenyl group has a molecular weight of from about 2,000 to about 4,000. 